Z-axis balance mechanism and bridge type three-coordinate measuring machine

Abstract

The utility model relates to the technical field of measuring equipment, in particular to a Z-axis balancing mechanism and a bridge type three-coordinate measuring machine, the Z-axis balancing mechanism comprises a Z-axis supporting seat arranged on a horizontal cross beam of the measuring machine, a Z axis is installed on the Z-axis supporting seat through a guide structure, a balancing cylinder is fixed on one side, far away from the Z axis, of the Z-axis supporting seat, and the Z-axis supporting seat is fixed on the horizontal cross beam of the measuring machine. The Z-axis balancing mechanism further comprises a flexible transmission part, one end of the flexible transmission part is connected with the Z axis, and the other end of the flexible transmission part is connected with the Z-axis supporting seat after bypassing the fixed pulley and the movable pulley, so that the balance cylinder balances the weight of the Z axis, the balance cylinder is independently arranged outside the Z axis, the weight of the Z axis is reduced, and the balance effect is improved. And meanwhile, the balance cylinder and the Z shaft are separately arranged on the two sides of the Z shaft supporting seat, so that the gravity center of the Z shaft balance mechanism can be close to the cross beam of the measuring machine as much as possible, and the influence of the Z shaft lifting action on the stability of the whole structure is reduced.

Description

Technical Field

[0001] This utility model relates to the field of measuring equipment technology, specifically to a Z-axis balancing mechanism and a bridge-type coordinate measuring machine. Background Technology

[0002] A measuring machine typically includes a probe, a motion system, and a marble platform. The probe is mounted on the motion system, which moves the probe relative to the marble platform.

[0003] Taking a coordinate measuring machine (CMM) as an example, the CMM's motion system includes mutually perpendicular X-axis, Y-axis, and Z-axis drive structures, used to control the movement of the probe relative to the marble platform in the X, Y, and Z directions, respectively. The Z-axis drive structure generally includes a Z-axis mounting bracket, the Z-axis, a drive motor, and a balance cylinder. The Z-axis is mounted on the X-axis slide via a guide structure and can move linearly in the vertical direction under the guidance of the guide structure. The X-axis slide is mounted on the X-axis crossbeam and can move linearly along the X-axis direction under the guidance of the X-axis crossbeam, allowing the Z-axis to adjust its position in the X-axis direction along with the X-axis slide. The Z-axis mounting bracket is fixed to the X-axis slide, together forming the Z-axis support. The balance cylinder is embedded in the Z-axis, with one end of the piston rod connected to the Z-axis mounting bracket. By controlling the air pressure, the weight of the Z-axis can be balanced, stabilizing the Z-axis for movement. The drive motor drives the Z-axis to move vertically.

[0004] Since the Z-axis is a vertically elongated structural component and its movement direction is up and down, the center of gravity of the Z-axis drive structure will change significantly in the vertical direction during the up and down movement of the Z-axis. For measuring machines with micron-level precision, a large range of changes in the center of gravity position will have a significant impact on the accuracy of the measuring machine. Utility Model Content

[0005] This invention solves the technical problem that the large range of changes in the center of gravity position of the Z-axis drive structure during Z-axis movement significantly affects the measurement accuracy of the measuring machine.

[0006] In a first aspect, the Z-axis balancing mechanism provided by this utility model includes:

[0007] Z-axis support is used to be mounted on the horizontal beam of the measuring machine so that it can move linearly along the horizontal beam;

[0008] The Z-axis is mounted on the Z-axis support via a guide structure and can move linearly under the guidance of the guide structure.

[0009] A balance cylinder is fixed on the Z-axis support and located on the side of the Z-axis support away from the Z-axis. The actuating end of the balance cylinder that outputs power has a movable pulley.

[0010] The Z-axis support is provided with a fixed pulley, and the Z-axis balancing mechanism also includes a flexible transmission component. One end of the flexible transmission component is connected to the Z-axis, and the other end passes around the fixed pulley and the movable pulley and is connected to the Z-axis support, so that the balancing cylinder can balance the weight of the Z-axis.

[0011] In one technical solution, the Z-axis support has a sleeve portion for being fitted onto the horizontal beam, and one of the cylinder body and piston rod of the balance cylinder that is fixed to the Z-axis support is a fixed portion, and at least a portion of the fixed portion is located below the top of the sleeve portion.

[0012] In one technical solution, a portion of the balance cylinder is located on the upper side of the sleeve portion, and the balance cylinder is inclined toward the Z-axis.

[0013] In one technical solution, there are at least two movable pulleys.

[0014] In one technical solution, at least part of the fixed pulley is an adjustable fixed pulley, and the position of the adjustable fixed pulley is adjustablely arranged on the Z-axis support, so that by adjusting the position of the adjustable fixed pulley, the flexible transmission member can be partially parallel on both sides of the movable pulley.

[0015] In one technical solution, the adjustable pulley is mounted on the Z-axis support via a wheel frame. The adjustable pulley is rotatably mounted on the wheel frame. At least one of the wheel frame and the Z-axis support has an adjusting elongated hole. The wheel frame is mounted on the Z-axis support via a threaded fastener passing through the adjusting elongated hole, so as to achieve adjustable mounting of the adjustable pulley on the Z-axis support.

[0016] In one technical solution, the Z-axis balancing mechanism further includes a drive mechanism, and at least one of the fixed pulleys is connected to the drive mechanism for transmission, so that the Z-axis can be moved by being driven to rotate through the fixed pulleys.

[0017] In one technical solution, the flexible transmission component is a strip structure.

[0018] In one technical solution, the Z-axis balancing mechanism further includes a safety rope, one end of which is connected to the Z-axis and the other end of which is connected to the Z-axis support. The Z-axis balancing mechanism also includes a safety rope pulley coaxially arranged with each of the fixed pulleys and the movable pulleys. The safety rope passes around the safety rope pulley and is arranged side by side with the flexible transmission member and has the same winding path.

[0019] Secondly, this utility model provides a bridge-type coordinate measuring machine, which includes a measuring platform, a measuring head, and a motion system. The measuring platform is used to carry the workpiece to be measured. The measuring head is disposed on the motion system so that the motion system moves the measuring head relative to the measuring platform. The motion system includes a Z-axis drive structure, which has a Z-axis balancing mechanism. The Z-axis balancing mechanism is the Z-axis balancing mechanism mentioned in the first aspect.

[0020] The beneficial effects of this utility model are as follows:

[0021] In this invention, the balance cylinder of the Z-axis balancing mechanism of the bridge-type coordinate measuring machine is set separately from the Z-axis and fixedly. Compared with the traditional structure where the balance cylinder is embedded in the Z-axis and moves with it, this reduces the weight of the Z-axis. Furthermore, the pulley system includes a movable pulley, which reduces the stroke of the balance cylinder. Therefore, a balance cylinder with a smaller stroke can be selected, reducing the weight and space occupied by the Z-axis balancing mechanism and minimizing the change in the center of gravity when the balance cylinder moves. Thus, the position of the balance cylinder does not change when the Z-axis is raised or lowered, reducing the range of change in the center of gravity of the Z-axis balancing mechanism in the vertical direction. At the same time, the balance cylinder and the Z-axis are placed on opposite sides of the Z-axis support, making the center of gravity of the Z-axis balancing mechanism closer to the horizontal beam of the measuring machine, reducing the gravitational lever arm, and preventing a large range of change in the center of gravity of the Z-axis balancing mechanism and Z-axis drive structure during Z-axis raising or lowering, which could affect the accuracy of the measuring machine. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of one embodiment of the bridge-type coordinate measuring machine of this utility model;

[0023] Figure 2 This is a front view of the Z-axis balancing mechanism of an embodiment of the bridge-type coordinate measuring machine of this utility model;

[0024] Figure 3 This is an axonometric view of the Z-axis balancing mechanism of an embodiment of the bridge-type coordinate measuring machine of this utility model;

[0025] Figure 4 This is a schematic diagram of a safety rope pulley and a first fixed pulley arranged coaxially in one embodiment of the bridge-type coordinate measuring machine of this utility model.

[0026] List of feature names corresponding to the labels in the figure:

[0027] 1. Measurement platform;

[0028] 2. Motion system; 21. Z-axis; 22. Z-axis support; 221. Sleeve body; 222. Fixing frame; 23. Air bearing guide rail; 24. Balance cylinder; 25. Flexible transmission component; 26. First fixed pulley; 27. Movable pulley; 28. Drive wheel; 29. ​​Second fixed pulley; 210. Wheel frame; 211. Safety rope; 212. Safety rope pulley.

[0029] 3. Probe. Detailed Implementation

[0030] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0031] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments, and the operational steps involved in each embodiment can also be rearranged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the specification and drawings are only for clearly describing a particular embodiment and do not imply that they represent the necessary components and / or order.

[0032] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0033] In this embodiment of the invention, to ensure the measurement accuracy of the bridge-type coordinate measuring machine, the balance cylinder and the Z-axis in the Z-axis balancing mechanism are set separately. The balance cylinder is fixedly mounted to prevent large-scale changes in the center of gravity of the Z-axis balancing mechanism during Z-axis movement. Simultaneously, the moving end of the balance cylinder has a movable pulley, which reduces the cylinder's operating distance. A cylinder with a smaller stroke can be selected. Furthermore, the balance cylinder and the Z-axis are placed on opposite sides of the Z-axis support, bringing the center of gravity of the Z-axis balancing mechanism closer to the horizontal beam of the measuring machine, reducing the leverage arm. This reduces the change in the center of gravity of the Z-axis balancing mechanism during Z-axis movement, ensuring the measurement accuracy of the measuring machine.

[0034] An embodiment of the bridge-type coordinate measuring machine of this utility model:

[0035] In one embodiment, please refer to Figure 1 The bridge-type coordinate measuring machine includes a measuring platform 1, a motion system 2, and a probe 3. The measuring platform 1 is used to carry the workpiece to be measured. The motion system 2 includes an X-axis drive structure, a Y-axis drive structure, and a Z-axis drive structure. The probe 3 is mounted on the Z-axis drive structure so that the position of the probe 3 can be adjusted by the motion system 2.

[0036] In a three-dimensional coordinate system, the X-axis, Y-axis, and Z-axis are mutually perpendicular. The X-axis and Y-axis are two mutually perpendicular horizontal directions, and the Z-axis is a vertical direction. Correspondingly, in a bridge-type coordinate measuring machine, the X-axis drive structure drives the probe 3 to move along the X-axis direction of the three-dimensional coordinate system, the Y-axis drive structure drives the probe 3 to move along the Y-axis direction of the three-dimensional coordinate system, and the Z-axis drive structure drives the probe 3 to move along the Z-axis direction of the three-dimensional coordinate system.

[0037] The Z-axis drive structure has a Z-axis balancing mechanism, which includes a Z-axis 21, with the probe 3 mounted at the lower end of the Z-axis 21. Please refer to [reference needed]. Figure 2 The Z-axis balancing mechanism also includes a Z-axis support seat 22, which is used to be mounted on the X-axis crossbeam of the measuring machine. The X-axis crossbeam is a horizontal crossbeam whose length extends along the X-axis direction, so that the Z-axis support seat 22 can move linearly along the X-axis crossbeam.

[0038] In one embodiment, the X-axis beam has a rectangular cross-section, and the Z-axis support 22 has a rectangular frame-structured sleeve portion 221, with fixing brackets 222 fixed to the sleeve portion 221. The sleeve portion 221 is mounted on the X-axis beam via a guide structure, allowing it to move linearly along the X-axis beam under its guidance. The guide structure can be any existing installation structure that enables the sleeve portion 221 to slide on the X-axis beam and guides its movement path; for example, it can be a structure with multiple air-bearing blocks on the inner circumferential surface of the sleeve portion 221. Alternatively, the guide structure can consist of a guide rail on the X-axis beam and a groove on the Z-axis support 22. In other embodiments, the Z-axis support 22 can also have other structural forms, such as a block structure.

[0039] Z-axis 21 is mounted on Z-axis support 22 via another guide structure. Please refer to [reference needed] for details. Figure 2 Two air-bearing guide rails 23 are arranged vertically and vertically on one side of the sleeve portion 221 of the Z-axis support 22. The Z-axis 21 is installed inside the air-bearing guide rails 23, so that the Z-axis 21 can move vertically under the guidance of the air-bearing guide rails 23. The Z-axis 21 is installed on the side of the Z-axis support 22, so that the Z-axis 21 is located on one side of the X-axis crossbeam.

[0040] In other embodiments, for the guide structure that enables the Z-axis 21 to be mounted on the Z-axis support 22, a vertically extending guide rod can be provided on the Z-axis support 22, and a guide sleeve can be provided on the Z-axis 21. The guide sleeve and the guide rod sleeve cooperate to guide the movement of the Z-axis 21. Alternatively, a vertically extending dovetail slide rail can be provided on the Z-axis support 22, and a dovetail slide groove can be provided on the side of the Z-axis 21. The dovetail slide rail and the dovetail slide groove cooperate to guide the movement of the Z-axis 21.

[0041] To balance the weight of the Z-axis 21, the Z-axis balancing mechanism also includes a balancing cylinder 24. In one embodiment, the balancing cylinder is a pneumatic cylinder, and the balancing cylinder 24 is also fixed on the Z-axis support 22, specifically on the mounting bracket 222. The balancing cylinder 24 and the Z-axis 21 are positioned on the left and right sides of the Z-axis support 22, respectively, so that the center of gravity of the Z-axis balancing mechanism and the Z-axis drive structure are as close as possible to the horizontal beam of the measuring machine, reducing the gravitational lever arm. In other embodiments, the balancing cylinder can also be a hydraulic cylinder.

[0042] The actuating end of the balance cylinder 24 is connected to the Z-axis 21 via a flexible transmission component 25. In this way, when the drive mechanism drives the Z-axis 21 to move up and down, the weight of the Z-axis 21 can be balanced by controlling the pressure of the balance cylinder 24.

[0043] In one embodiment, please refer to Figure 2 The cylinder body of the balance cylinder 24 is a fixed part that is fixedly connected to the fixed frame 222. This ensures that its position does not change during the movement of the Z-axis 21, minimizing the change in the center of gravity of the balance cylinder 24, and consequently lowering the center of gravity of the entire Z-axis balancing mechanism and Z-axis drive structure, thus improving the stability of the mechanism. The lower end of the cylinder body is positioned below the top of the sleeve portion 221, further lowering the center of gravity of the balance cylinder 24. Furthermore, the portion of the balance cylinder 24 located on the upper side of the sleeve portion 221 is inclined towards the Z-axis 21, thereby fully utilizing the space on the upper side of the sleeve portion 221 and making the overall layout of the Z-axis balancing mechanism more compact. In other embodiments, provided that the space of the measuring machine meets the design requirements, the balance cylinder 24 can be arranged vertically, or it can be entirely located on the upper side of the sleeve portion 221.

[0044] In one embodiment, the Z-axis balancing mechanism further includes a first fixed pulley 26 mounted on a fixed frame 222, a movable pulley 27 at the actuating end of the balancing cylinder 24, and a flexible transmission member 25 with one end connected to the Z-axis 21 and the other end connected to the fixed frame 222 after passing over the first fixed pulley 26 and the movable pulley 27. Because of the movable pulley 27 in the pulley system, the stroke of the balancing cylinder 24 can be reduced, thereby reducing the range of center of gravity changes during Z-axis balancing mechanism operation. Simultaneously, a balancing cylinder with a shorter stroke can be used, reducing the space occupied by the balancing cylinder, lowering the center of gravity of the Z-axis balancing mechanism and the Z-axis drive structure, and also reducing the procurement cost of the balancing cylinder.

[0045] The first fixed pulley 26 is coaxially connected to the drive wheel 28, making the first fixed pulley 26 a drive pulley. The drive wheel 28 is connected to a drive mechanism, such as a belt driven by a motor, and can be driven to rotate by the drive mechanism, thereby driving the flexible transmission member 25 to change the height of the Z-axis 21. Regarding the specific form of the flexible transmission member 25, in one embodiment, the flexible transmission member 25 is a steel belt. The steel belt has a larger contact surface with the first fixed pulley 26, resulting in smoother movement and effectively suppressing vibration. In other embodiments, the flexible transmission member 25 can also be a synchronous belt, a belt, or other similar belt-like structures; of course, it can also be a steel wire rope, high-strength fiber rope, etc. The first fixed pulley 26 can be a drum, thereby enabling the flexible transmission member to be corrected. In other embodiments, more fixed pulleys can be provided and connected to the drive mechanism as drive wheels, such as two or more.

[0046] In other embodiments, the drive mechanism in the Z-axis drive structure can also be a belt drive. Specifically, a clamping block is fixed at the end of the Z-axis, and the clamping block is clamped to the belt, so that the belt can drive the Z-axis to rise and fall.

[0047] In one embodiment, please refer to Figure 2 and Figure 3 The fixed frame 222 is also equipped with a second fixed pulley 29, which is an adjustable fixed pulley. The second fixed pulley 29 is positioned between the movable pulley 27 and the first fixed pulley 26. The flexible transmission member 25 also bypasses the second fixed pulley 29. By adjusting the position of the second fixed pulley 29, the flexible transmission member 25 can be made parallel to the parts on both sides of the movable pulley 27. Regarding the number of movable pulleys 27 and second fixed pulleys 29, in one embodiment, there are two movable pulleys 27, so that the stroke of the balance cylinder 24 is 1 / 4 of the Z-axis 21, and there are also two second fixed pulleys 29. In other embodiments, the number of movable pulleys can be only one or more than two, such as three or four, etc., and the number of second fixed pulleys 29 is not less than the number of movable pulleys.

[0048] Of course, if we do not consider whether the parts of the flexible transmission component 25 located on both sides of the movable pulley 27 are parallel, or if we can ensure that the parts of the flexible transmission component 25 located on both sides of the movable pulley 27 are parallel by setting the positional relationship between the movable pulley and the first fixed pulley, then we may not set the second fixed pulley.

[0049] To achieve adjustable position of the second fixed pulley 29, the second fixed pulley 29 is mounted on the fixed frame 222 via a wheel bracket 210. The second fixed pulley 29 is rotatably mounted on the wheel bracket 210. At least one of the wheel bracket 210 and the fixed frame 222 has an adjustment elongated hole, which can be a slotted hole. The wheel bracket 210 is mounted on the fixed frame 222 via threaded fasteners passing through the adjustment elongated hole, thereby achieving adjustable position of the second fixed pulley 29 on the fixed frame 222. In other embodiments, for the adjustable position of the second fixed pulley 29 on the fixed frame 222, multiple sets of fixing holes can be provided at intervals on the fixed frame, and the wheel bracket has mounting holes. By aligning the mounting holes with the fixing holes at different positions and inserting threaded fasteners, the adjustable position of the second fixed pulley on the fixed frame can be achieved.

[0050] Under normal circumstances, the flexible transmission component 25 continuously suspends the Z-axis 21. However, if the flexible transmission component 25 breaks, the Z-axis 21 may fall, causing the probe 3 to collide with the measuring platform 1. To address this, this invention incorporates a safety rope 211. One end of the safety rope 211 is connected to the Z-axis 21, and the other end is connected to the fixed frame 222. Furthermore, a safety rope pulley 212 is coaxially mounted for each movable pulley 27, the first fixed pulley 26, and the second fixed pulley 29. Please refer to [reference needed]. Figure 3 and Figure 4 This ensures that after the safety rope 211 passes around each safety rope pulley 212, it is arranged side by side with the flexible transmission component 25 and has the same winding path.

[0051] When the Z-axis 21 is working normally, the safety rope 211 is looser than the flexible transmission component 25. Therefore, in the event of a breakage of the flexible transmission component 25, the safety rope 211 can prevent the probe 3 from colliding with the measuring platform 1. The safety rope 211 can be made of steel wire, high-strength fiber, etc.

[0052] This invention also provides a Z-axis balancing mechanism, which has the same structure as the Z-axis balancing mechanism of the bridge-type coordinate measuring machine in the above embodiments, and will not be described again here. This Z-axis balancing mechanism can be applied to bridge-type coordinate measuring machines, as well as gantry-type coordinate measuring machines, cantilever coordinate measuring machines, etc.

[0053] The above-described specific examples are for illustrative purposes only and are not intended to limit the scope of this invention. Those skilled in the art to which this invention pertains can make various simple deductions, modifications, or substitutions based on the concept of this invention.

Claims

1. A Z-axis balancing mechanism, characterized by, The application relates to a Z-axis balancing mechanism. The Z-axis support base is provided with a fixed pulley, and the Z-axis balancing mechanism further comprises a flexible transmission member, one end of the flexible transmission member being connected with the Z-axis, the other end of the flexible transmission member being connected with the Z-axis support base after passing through the fixed pulley and the movable pulley, so that the balancing cylinder can balance the weight of the Z-axis. The Z-axis support base has a sleeve part for being sleeved on the horizontal cross beam, one of the cylinder body and the piston rod of the balancing cylinder fixed with the Z-axis support base is a fixed part, and at least part of the fixed part is located below the top of the sleeve part. The movable pulley has at least two. At least part of the fixed pulley is an adjustable fixed pulley, the adjustable fixed pulley is adjustably arranged on the Z-axis support base, so that the parallelism of the parts of the flexible transmission member on both sides of the movable pulley can be realized by adjusting the position of the adjustable fixed pulley.

2. The Z-axis balancing mechanism of claim 1, wherein, The adjustable fixed pulley is installed on the Z-axis support base through a wheel frame, the adjustable fixed pulley is rotatably installed on the wheel frame, at least one of the wheel frame and the Z-axis support base is provided with an adjusting long hole, and the wheel frame is installed on the Z-axis support base through a threaded fastener arranged in the adjusting long hole, so that the adjustable fixed pulley is adjustably installed on the Z-axis support base.

3. The Z-axis balancing mechanism of claim 2, wherein, The Z-axis balancing mechanism further comprises a driving mechanism, at least one of the fixed pulleys is in transmission connection with the driving mechanism, so that the Z-axis is driven to move through the rotation of the fixed pulley.

4. The Z-axis balancing mechanism of claim 1, wherein, The flexible transmission member is in a belt structure.

5. The Z-axis balancing mechanism according to any one of claims 1 to 4, wherein The Z-axis balancing mechanism further comprises a safety rope, one end of the safety rope being connected with the Z-axis and the other end of the safety rope being connected with the Z-axis support base, the Z-axis balancing mechanism further comprises safety rope pulleys coaxially arranged with the fixed pulleys and the movable pulley respectively, the safety rope passes through the safety rope pulleys, so as to be arranged side by side with the flexible transmission member and have the same rope winding path.

6. The Z-axis balancing mechanism of claim 5, wherein, The Z-axis balancing mechanism is the Z-axis balancing mechanism as claimed in any one of claims 1-9.

7. The Z-axis balancing mechanism of any one of claims 1-4, wherein, ​ 8. The Z-axis balancing mechanism of claim 7, wherein, ​ 9. The Z-axis balancing mechanism of any one of claims 1-4, wherein, ​ 10. A bridge-type three coordinate measuring machine comprising a measuring stage for carrying a workpiece under test, a measuring head arranged on a motion system for movement of the measuring head relative to the measuring stage by the motion system, the motion system comprising a Z-axis drive structure having a Z-axis counterbalance mechanism, characterised in that, ​

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